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Natural Hazards. GLG-110 Instructor Kevin F. Mullins. We live on a fairly small, rocky planet that circles a common, ordinary star that is in turn a miniscule part of an average galaxy. Five things make our planet somewhat extraordinary by the standards we know today: 1) it is very dynamic
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Natural Hazards GLG-110 Instructor Kevin F. Mullins
We live on a fairly small, rocky planet that circles a common, ordinary star that is in turn a miniscule part of an average galaxy. Five things make our planet somewhat extraordinary by the standards we know today: 1) it is very dynamic 2) it contains water in all three physical phases 3) it orbits it’s star in the “Goldilocks Zone” 4) it has a large moon to-planet-ratio 5) it is crawling with carbon-based life forms Earth
Natural Hazards, Disasters, Catastrophes Definitions : • Hazard: any natural process that poses a threat to human life or property • Disaster: the effect of a hazard on society • Usually as an event expending high levels of energy • Of limited duration and extent • Catastrophe: a massive disaster requiring significant expenditures in time, effort and money for recovery • Note : due to our anthropocentric outlook, without people there are no hazards, disasters, or catastrophes, these become only natural events
Some questions this class hopes to address • What types of hazards pose threats? • What is the level of threat? • Where is each type of hazard likely to occur, how often and why? • How often do these hazards develop into disasters? Catastrophes? • How can each type of disaster be predicted and/or mitigated?
Why study natural hazards? • Injuries and mortality • Economic impacts • Disruption of “normal” life cycles • Disruption/destruction of communications, transport, services, products • Prediction of location, timing, and/or magnitude of future events • Planning for mitigation of post-event affects • Emergency medical and social services • Alternate energy and food supplies • Avert or minimize impact of future events • Planning • Education • Institution of zoning, codes, etc.
Worldwide natural hazards • Figures include 20th century occurrences • US tornado stats are for 1990-1995 period only • Note scale of events in Africa • Stable continent • Few tropical storms develop • Disproportionably affected by drought
U.S. Tornados & fatalities 2008-2011 http://spc.noaa.gov/climo/online/monthly/newm.html
Where are the events with the highest number of fatalities (since 1970)? Why?
Events with highest fatalities • Worldwide totals since 1970
Where are the events that produce the highest damage costs (since 1970)? Why?
Events with highest costs • Worldwide totals since 1970
Frequency of hazards • Worldwide totals for 20th century • US tornados > over last half of 20th to 250/yr • More than any other hazard
History’s Role • Fundamental understanding that these are repetitive events • Documenting and analyzing event parameters provides a base for understanding processes and estimating : • event probabilities • risk potential • impact zones • damage estimates • Use physical manifestations (flood deposits, channels, lava flows, etc) to detail events, locations, paths, timing, and processes
Processesthe physical, chemical and biologic ways events affect the Earth’s surface • Internal • Igneous • Seismic • Plate tectonic • External • Solar • Atmospheric • Hydrologic • Gravity
Hazard Cycles • Tectonic • Large-scale processes that deform the Earth’s crust and create regional landforms • Control most volcanic and seismic events • Mountains • Ocean/land basins • Continents • Creation and destruction of crustal material • Rock • Igneous • Sedimentary • Metamorphic • Any rock can be produced from any other type of rock • Hydrologic • The movement of water from the Earth’s interior, to the oceans, atmosphere, surface and subsurface • Biogeochemical • The transfer of elements through the atmosphere, lithosphere, hydrosphere and biosphere due to the activity of living organisms
Fundamental Concepts • Prediction • Risk analysis • Linkages (integration) • Scale growth • Mitigation
Fundamental ConceptsPrediction • Natural processes • Natural processes are a part of our dynamic Earth • Become hazards when they threaten life, property, and culture • Prediction • Using history and current technology (and common sense) to acquire detailed knowledge of where an event may occur • Probability • Using history and technology to calculate the probability of an occurrence and its magnitude • Forecasting • Precursor events • Technology in the right place and looking for the right parameters • Good at some not so good at others • Warnings • Issued from knowledgeable scientists, confirmed, reviewed and validated by informed group, to the appropriate decision makers, to the appropriate local authorities, to the public
Fundamental ConceptsRisk Assessment • Risk – the probability of a specific event occurring X the consequences should it happen • Probability • > P for smaller event • < P for larger event • Consequences vary by magnitude of failure • Fracture of a road surface • Fracture of a nuclear power plant cooling system • Acceptable risk • For individual and society depends on situation • Driving vs living on slope of active volcano • > 6M accidents 1999 • ~112 people killed each day • Mt. Rainier - 1840 • Can be difficult to calculate if data is lacking
Fundamental ConceptsIntegration Between hazards Hurricanes Flooding Coastal erosion Slope failure Lightning Earthquakes Tsunami Mass movement Volcanism Climate change Flooding Drought Erosion Biochemical reactions
Fundamental ConceptsIntegration Between hazards Wildfires Destruction of vegetation & habitat Erosion of soils Flooding Pollution of habitat and destruction of ecology Volcanoes Tsunami Lahars/mudflows Floods Outgassing and acid rain Climate change Local vs global
Fundamental ConceptsIntegration • Between hazard and natural environment • Tectonic setting • Subduction zone creates EQ’s and andesitic volcanism • Rock composition • Shale or foliated rocks vs granite • Climate/Weather • Drought dries out vegetation resulting in wildfires • Wildfires destroy vegetation cover resulting in > surface flow, floods and erosion
Fundamental ConceptsScale Growth • Population growth • Exponential growth function • Moving into more dangerous areas • Stressing environment negative way • Magnitude/Frequency Concept • In general, frequency is inversely related to magnitude • Still a statistical measurement, so rare events do occur and sometimes within short periods of time
Fundamental ConceptsMitigation • Reactive vs proactive • Reactive = responding to each event as needed • Never solves root problem • Proactive = using information gleaned from each event in planning how to mitigate next • Can solve root problem and possibly avoid reoccurrence • Impact and recovery • Depends on • Magnitude of event • Location of event • Preparation of population • Phases of recovery • Emergency • Restoration • Reconstruction I • Reconstruction II
Benefits of Natural Disasters • Floods • Hurricanes • Tornadoes • Volcanoes • Earthquakes • Tsunami • Wildfires • Drought • Blizzards • Landslides • Meteorite Impacts • Climate Change • Biologic
Geological Concepts • Catastrophism – the hypothesis that the Earth evolved through a series of sudden and violent upheavals • Uniformitarianism - James Hutton Scottish naturalist in 18th century proposed that the processes we see today can be used to interpret the rock record of past geological events (“present is the key to the past”). These processes are small, physical, chemical and biological processes working slowly over time and resulting in the world we see today.
Geological Concepts(continued) • Plate Tectonics – • 1) The upper crust and mantle (Lithosphere) are composed of rigid plates (7 major and 8 minor) • 2) The plates move slowly relative to each other (centimeters/yr) • 3) Most of Earth’s large-scale activity (earthquakes, volcanoes, etc) occurs along plate boundaries • 4) The plate interiors are generally quiet.
